During the production of insulating glass with spacers that are made of deformable, e.g., thermoplastic, material, the procedure is such that, for example, a strand made of deformable material, which is to form the spacer, is applied (“sprayed on”) to a glass pane, whereby the strand is located some distance (“recess”) from the edge of the glass pane, i.e., is mounted offset inward relative to the edge of the glass pane. After the strand, which forms the spacer, has been applied, the beginning and the end of the strand are connected to one another, for example by the overlapping ends of the strand being compressed.
After the spacer made of deformable material has been closed, a second glass pane is put into place (the insulating glass blank is assembled), and the insulating glass blank is compressed to form a desired distance in order to achieve the intended outside thickness (distance between the outside surfaces of the glass panes and the insulating glass blank from one another).
It is problematic that the corners of such spacers are not sharp-edged, but rather are made with more or less large radii. The corners of strands made of thermoplastic material formed in situ, which form spacers for insulating glass, are often made essentially in the shape of a quarter-circle arc.
For aesthetic reasons, it is also preferred to make the corners in spacers that are made of deformable, e.g., thermoplastic, material, sharp-edged, i.e., with corners that have a very small radius that is as optically imperceptible as possible.
Since the edge joint of an insulating glass blank that is open toward the outside is filled with sealing compound during the production of insulating glass, the problem arises that with corners of larger radii, i.e., rounded corners, the amount of sealing compound required cannot be easily adjusted.
When the corners are not rounded in the spacer but rather are made sharp-edged, less sealing compound is required in the corner area.
Insulating glass elements, which have sharp-edged corners in spacers, are also advantageous for reasons of insulation, in particular heat insulation (smaller heat transfer coefficient).
In the state of the art, various proposals have been made to produce corners in spacers that are made of thermoplastic material.
WO 94/06992 A thus describes the formation of a corner of prefabricated spacers that are made of plastic material, for example butyl rubber or polyisobutylene, whereby the ends of a prefabricated spacer lying in the area of a corner are connected to one another by tools to be placed from the outside and from the inside so that the spacer is closed.
DE 36 37 561 A deals with the application of prefabricated, flexible spacers on glass panels, whereby four systems are provided, with which the corners of a spacer can be formed. Using these systems, the corners of a prefabricated spacer that is in the shape of a quarter-circle arc in the corner area are to be deformed into a sharp corner. To this end, each of the systems has angular components, which are moved toward one another and away from one another using pressure medium motors. One of the angular components is installed from the outside, and the other angular component is placed from the inside on the spacer to be deformed in the corner area to form a sharp corner.
EP 1 018 590 A deals with the in-situ production of a spacer made of thermoplastic plastic, whereby a thermoplastic spacer is applied strand-like from a nozzle onto a glass pane, while the nozzle is moved along the edge of the glass pane. When forming corners, the nozzle is pivoted around an axis that is oriented perpendicular to the glass pane, whereby the nozzle is raised from the glass pane so that the strand made of plastic, which is expelled from the nozzle, does not adhere to the glass pane, while the nozzle is pivoted. The corners of spacers produced according to EP 1 018 590 A2 namely essentially have inner corners that are sharp, but outer corners that are rounded like a quarter-circle arc.
EP 0 152 807 A relates to a device, used in the course of the production of insulating glass, for applying a spacer made of plastic on a vertically-oriented glass pane. To form corners in the spacer, the glass pane, on which the spacer is applied, is to be pivoted, whereby a guide system is provided that is to support the forming of corners in the spacer.
From DE 43 26 179 A, a frameless glazing with a bonded window pane is known. In this case, a bead that forms a spacer is applied on a window pane. In the corner area formed by two ends of the bead that overlap one another, the corner is to be formed by means of a pressure mold tool.
DE 87 01 101 U1 discloses a method for forming at least one corner in spacers for insulating glass, whereby the spacer consists of a strand made of deformable material applied on the glass pane.
In the case of DE 87 01 101 U1, for forming the fourth corner in a prefabricated spacer, an end of the spacer projecting over the corner to be formed is picked up by a tool that acts as a clamp and is bent by the tool by 90°. A die that is provided in the case of DE 87 01 101 U1 has no influence on the shaping and forming of the corner, since it is effective only in the area of the point of contact between the ends of the spacer-forming strand, after the corner has been formed.